void multiply_CSRMat_CSVec(const CSRMat& A, const CSVec& x, CSVec& y)
{
//This function is unit-tested in fei/utest_cases/fei_unit_CSRMat_CSVec.cpp
const std::vector<int>& rows = A.getGraph().rowNumbers;
const int* rowoffs = &(A.getGraph().rowOffsets[0]);
const std::vector<int>& colinds = A.getGraph().packedColumnIndices;
const double* Acoef = &(A.getPackedCoefs()[0]);
const std::vector<int>& xind = x.indices();
const std::vector<double>& xcoef = x.coefs();
const double* xcoef_ptr = &xcoef[0];
const int* xind_ptr = &xind[0];
int xlen = xcoef.size();
std::vector<int>& yind = y.indices();
std::vector<double>& ycoef = y.coefs();
unsigned nrows = A.getNumRows();
yind.resize(nrows);
ycoef.resize(nrows);
int* yind_ptr = &yind[0];
double* ycoef_ptr = &ycoef[0];
int jbeg = *rowoffs++;
for(unsigned i=0; i<nrows; ++i) {
int jend = *rowoffs++;
double sum = 0.0;
while(jbeg<jend) {
int xoff = fei::binarySearch(colinds[jbeg], xind_ptr, xlen);
if (xoff > -1) {
sum += Acoef[jbeg]*xcoef_ptr[xoff];
}
++jbeg;
}
yind_ptr[i] = rows[i];
ycoef_ptr[i] = sum;
}
}
void add_CSVec_CSVec(const CSVec& u, CSVec& v)
{
const std::vector<int>& indices = u.indices();
const std::vector<double>& coefs = u.coefs();
for(size_t i=0; i<indices.size(); ++i) {
add_entry(v, indices[i], coefs[i]);
}
}
void remove_entry(CSVec& vec, int eqn)
{
std::vector<int>& v_ind = vec.indices();
std::vector<double>& v_coef = vec.coefs();
std::vector<int>::iterator
iter = std::lower_bound(v_ind.begin(), v_ind.end(), eqn);
if (iter != v_ind.end() && *iter == eqn) {
v_ind.erase(iter);
size_t offset = iter - v_ind.begin();
std::vector<double>::iterator coef_iter = v_coef.begin()+offset;
v_coef.erase(coef_iter);
}
}
void put_entry(CSVec& vec, int eqn, double coef)
{
std::vector<int>& v_ind = vec.indices();
std::vector<double>& v_coef = vec.coefs();
std::vector<int>::iterator
iter = std::lower_bound(v_ind.begin(), v_ind.end(), eqn);
size_t offset = iter - v_ind.begin();
if (iter == v_ind.end() || *iter != eqn) {
v_ind.insert(iter, eqn);
v_coef.insert(v_coef.begin()+offset, coef);
}
else {
v_coef[offset] = coef;
}
}
double get_entry(const CSVec& vec, int eqn)
{
const std::vector<int>& v_ind = vec.indices();
const std::vector<double>& v_coef = vec.coefs();
if (vec.size() == 0) {
throw std::runtime_error("get_entry error, CSVec is empty");
}
std::vector<int>::const_iterator
iter = std::lower_bound(v_ind.begin(), v_ind.end(), eqn);
if (iter == v_ind.end()) {
throw std::runtime_error("get_entry error, entry not found.");
}
return v_coef[iter - v_ind.begin()];
}
void multiply_trans_CSRMat_CSVec(const CSRMat& A, const CSVec& x, CSVec& y)
{
const std::vector<int>& rows = A.getGraph().rowNumbers;
const int* rowoffs = &(A.getGraph().rowOffsets[0]);
const int* colinds = &(A.getGraph().packedColumnIndices[0]);
const double* Acoef = &(A.getPackedCoefs()[0]);
const std::vector<int>& xind = x.indices();
const std::vector<double>& xcoef = x.coefs();
const double* xcoef_ptr = &xcoef[0];
unsigned nrows = A.getNumRows();
std::vector<int> offsets;
fei::impl_utils::find_offsets(rows, xind, offsets);
const int* offsetsptr = &offsets[0];
fei::CSVec fy;
int jbeg = *rowoffs++;
for(unsigned i=0; i<nrows; ++i) {
int jend = *rowoffs++;
int xoff = offsetsptr[i];
if (xoff < 0) {
jbeg = jend;
continue;
}
double xcoeff = xcoef_ptr[xoff];
while(jbeg<jend) {
add_entry(fy, colinds[jbeg],Acoef[jbeg]*xcoeff);
++jbeg;
}
}
y = fy;
}